A solenoid type fuel injection valve (injector) is known. The solenoid type fuel injection valve receives high pressure fuel from a delivery pipe, which accumulates fuel received from a high pressure pump that pumps fuel from a fuel tank. The fuel injection valve injects the received high pressure fuel into an internal combustion engine of a vehicle (e.g., an automobile).
For instance, JP2002-506502A (corresponding to U.S. Pat. No. 6,279,873B1) teaches such a fuel injection valve. Specifically, in a deenergized state of a coil of this fuel injection valve, a needle valve is urged by an urging force of a first return spring, so that the needle valve is seated against a valve seat. Furthermore, a movable core is urged against a stopper element by an urging force of a second return spring. At this time, a small gap is formed between a flange of the needle valve and the movable core.
At the time of executing a valve-opening operation, the coil is energized, so that the movable core is magnetically attracted to the stationary core, and the movable core abuts against the flange of the needle valve in the accelerated state of the movable core. In this way, a valve-opening time period, which is a time period required to open the injection hole by lifting the needle valve away from the valve seat, is shortened.
However, in the fuel injection valve of JP2002-506502A (corresponding to U.S. Pat. No. 6,279,873B1), both of the first return spring and the second return spring urge the movable core toward the fuel injection hole at the time of executing a valve-closing operation, which is executed to seat the needle valve against the valve seat. Therefore, when the state of the coil is changed from the energized state to the deenergized state, the movable core, which is moved together with the needle valve toward the injection hole, is urged by the urging force of the second return spring and the inertia of the movable core and thereby collides against the stopper element upon the seating of the needle valve against the valve seat. Thereafter, the movable core rebounds from the stopper element. When the collision force of the movable core against the flange of the needle is increased, a secondary valve-opening movement of the needle valve occurs to reopen the injection hole. Thereby, it may possibly be difficult to accurately control the fuel injection quantity of the fuel injection valve.
Furthermore, when the collision force of the movable core against the stopper element is increased, the collision noise may possibly be increased. Also, the collision of the movable core against the stopper element may possibly damage the movable core and/or the stopper element.